* {
    margin: 0;
    padding: 0;
}

.fly {
    width: 250px;
    height: 50px;
    background: #b0b0b0;
}
.fly span{
    float: left;
    line-height: 50px;
}
.fly-left {
    float: left;
    height: 50px;
    margin-left: 0px;
}
.fly:hover >.fly-left{
    margin-left: 10px;
    transition: all 2s;
}
.fly-left:hover {
    margin-left: 10px;
    transition: all 2s;
}
.fly-right  {
    opacity: 0;
    float: right;
    margin-right: 0px;
    height: 50px;
}
.fly:hover > .fly-right{
    opacity: 1;
    margin-right: 70px;
    transition: all 2s;
}
.fly-right:hover {
    opacity: 1;
    margin-right: 70px;
    transition: all 2s;
}